Oil-based frying is commonly used as a cooking method for a wide range of food products, such as poultry, fish, potato products, and the like. Commercial fryers include one or more fry pots that are filled with a cooking medium such as oil or solid fats. Heat is typically provided to the cooking medium using an electrical heating element submerged in the cooking medium or a gas burner thermally coupled to the cooking medium though the walls of the fry pot. When the cooking medium reaches a preset cooking temperature, food products are placed into the cooking medium for a predetermined amount of time during which the food products are cooked by heat from the cooking medium. To facilitate insertion and removal of the food products, the food products are typically placed inside a container, such as a wire basket, and the container is lowered into the cooking medium for the predetermined amount of time.
The cooking medium is normally re-used for multiple cooking cycles, which may include cooking cycles for different food products. However, the cooking medium degrades over time. This degradation may be due to contamination by particles shed by the food products being cooked and from chemical degradation due to heat, oxidation, and reactions with the food products. In addition, as food particles accumulate in the cooking medium, the flavor characteristics of the food particles may become infused in the cooking medium. This infusion may adversely affect the quality of cooked food. For at least these reasons, the cooking medium must occasionally be replaced.
To maintain cooking quality and to prolong the operational lifetime of the cooking medium, the cooking medium may be filtered periodically. The filtering process removes cooking by-products, such as suspended food particles ranging from dust-sized particles to larger pieces of crackling and small pieces of food product. Frequent filtering may extend the useful life of the cooking medium, thereby reducing the cost of operating the fryer by reducing the frequency with which the cooking medium must be replaced. The cost savings from filtering may be particularly beneficial when using a cooking medium that contains reduced amounts of transfats, which have become popular, but are typically more expensive than other types of cooking media. Thus, it may be economically beneficial to frequently filter the cooking medium to extend its useful life.
Some conventional pressure and open fryers include automated oil management systems which route oil through fryer subsystems to accomplish oil management tasks such as recirculation, filtering, and discarding used oil. To avoid mixing multiple types of cooking media in a vessel, some conventional fryer systems use a system of plumbing, such as pumps, check valves, and solenoid valves to regulate the return of the cooking medium to the fryer from which the cooking medium was filtered. In some conventional fryers, each cooking vessel may have its own corresponding pumps, check valves, and solenoid valves.
In some systems, as many as eight fry pots or divided cooking chambers are included in each fryer. These additional parts cause the fryer to take up a larger space than would otherwise be necessary. Further, the additional piping and cooking medium routing elements require more cooking medium than otherwise would be necessary for a fryer system using some shared components. In the interest of increasing throughput by providing a greater number of fry pots while maintaining efficient use of space, there is a need to reduce the amount of space required to house the components of the fryer. To this end, it is desirable to enable a plumbing system to operate with multiple different fry ports or cooking chambers.
A previous version of a solution to address some of these problems is shown at U.S. Pat. No. 9,528,510, which is owned by the original assignee of this disclosure. That patent provides a multiport rotary valve for directing flow between one or more cooking medium sources and one or more cooking chambers. The position control for the valve is performed mechanically with cams and switches in this version. The mechanical cams and switches are subject to wear out and/or be affected in operation when oil vapor or water is present, which may occur in the environment fryers are located. To this end, the generally harsh environmental conditions (temperature and oils/dusts in the air) around fryers can make it difficult to assure reliability of sensors and control systems for such valves. If the position sensing of the rotary valve becomes inaccurate, cooking medium being filtered through a filtration system could potentially be routed back to the wrong cooking chamber, and as such, it would be desirable to develop a system that avoids such possibilities.